Pitch blocks



l. E. WHITE PITCH BLOCKS May 24, 1966 2 Sheets-Sheet 1 Filed April 4, 1962 RE 07 T/ NHM WW 5 G. W V my V B 28 4 3 FIG. 3.

y 4, 1966 I. E. WHITE 3,252,317

PITCH BLOCKS Filed April 4, 1962 2 Sheets-Sheet 2 INVENTOR.

50 FIG, 2 /Al///V6 E. A/H/TE ,4 TTORA/E 7 5 United States Patent PITCH BLOCKS Irving E.'White, Grand Rapids, Mich., assignor to Michigan Wheel Company, Grand Rapids, Mich., a corporation of Michigan I Filed Apr. 4, 1962, Ser. No. 185,106 7 Claims. (Cl. 72457) This invention relates to pitch blocks for shaping marine propeller blades, and more particularly to a pitch block assembly having a universal mounting base and an interchangeable forming surface.

Pitch blocks, commonly used for shaping marine propeller blades-to proper pitch, are conventionally unitary, massive, heavy castings. Strength and massiveness are essential since the blades are shaped on these blocks by hammering.

Propellers are used in a variety of sizes and pitches.

The individual pitch blocks are each for-med with a different surface configuration. A series of the cast blocks are normally stocked so that together they provide a multiplicity of different blade-matching surfaces of a variety of pitches and propeller sizes. Thus, each repair shop normally must stock a complete array of pitch block castings to service the variety of propellers encountered. This array not only consumes a large amount of space in a service shop, but also involves a costly inventory, especially as the range of propeller variations increases year by year. The cost of shipping these heavy pitch blocks is also a substantial disadvantage.

It is an object of this invention to provide a novel pitch block assembly which eliminates the need for stocking a large array of heavy, massive and costly pitch block castings. The large shipping costs involved are reduced to a minor amount. The inventive pitch block assembly further frees a great deal of service shop space normally consumed by storage of pitch block castings of v conventional constructions.

It is another object of this invention to provide these space saving, economical features while enabling each service shop to repair any of the variety of marine propellers encountered. To service new propellers as they develop, only a small additional expense is necessary for supplementary components. This invention has accomplished this purpose without sacrifice of accuracy. This is most important, since the efiiciency of the propeller is sensitive to the accuracy of the pitch of the blades.

These and other objects of this invention will be apparent upon studying the following specification in conjunction with the drawings in which:

FIG. l is a front elevational view of the novel pitch block assembly showing in phantom a propeller mounted thereon;

FIG. 2 is a top plan view of the universal base of the assembly illustrated in FIG. 1;

FIG. 3 is a sectional view taken on plane III-III of the base illustrated in FIG. 2;

FIG. 4 is a side elevational view of the base illustrated in FIG. 2; a

FIG. 5 is a bottom view of one forming plate adapted to interfit with the universal base illustrated in FIGS. 2 through 4, to form the assembly illustrated in FIG. 1;

FIG. 6 is a side elevational view of the plate illustrated in FIG. 5;

FIG. 7 is a sectional view of the plate taken on plane VII-VII of FIG. 5; and

FIG. 8 is a fragmentary, enlarged view of the interfitting plate portions and base support.

Basically, the invention comprises a pitch block assembly including a universal support base having means for mounting a propeller hub so that a blade of the "ice propeller extends over the base, and an accurately aligned forming plate removably connected to the base beneath the propeller blade. The plate includes circumferential alignment means, preferably comprising a plurality of accurately machined tapered projections adapted to inter: fit with accurately machined corresponding tapered slots in the base to align the plate with respect to the hub mounting means. A clearance exists between the bottom of the projections and the slots to prevent interference with the vertical alignment means. The underside of each plate includes accurately machined vertical alignment means preferably comprising a plurality of adjacent spaced pads of varied height, adapted to firmly rest against a support area of the universal base. Radial spacing means for regulating displacement of the plate from the hub mounting means is achieved .by cooperation of studs,,stud receivingorifices in the plate, and threaded sockets in the base.

Referring to the drawings, in FIG. 1 the pitch block assembly 10 has a marine propeller 12 (shown in phantom) mounted thereon so that one blade 14 extends over the particular forming plate 16 used in the assembly. The plate is removably mounted to the universal support base 18. The support base includes a laterally extending,

lower platform 20 into which a suitable hub mounting shaft 24 is fitted. The upper end of the shaft fits into the hub 13 of the propeller. If the axial hub opening is larger, a shaft having a larger upper end may be used, or bushings may be added.

The support base, shown more specifically in FIGS. 2, 3, and 4, is a universal element of the assembly that can be used with any different forming plate depending upon the size, pitch, and/or configuration of propeller blade to be shaped. Thus, a service shop need only stock one base casting and a plurality of the relativelysmall, lightweight supplementary plate forming elements to service the variety of marine propellers encountered. Re-

movable connection between the forming plate and the base is achieved with a pair of connecting ears 50, 52 on the plate having openings therein 54, 56 adapted to receive threaded studs 58, 60 (FIG. 1), and cooperating with threaded sockets 40, 42 of bosses 36, 38 on the base.

To provide circumferential alignment of the desired plate with respect to the hub mounting orifice 22 of the universal base 18, a pair of tapered slots 28, 30 with accurately machined side edges is provided in the upper support area 32 of the base, These tapered slots are shown positioned adjacent the pair of laterally projecting bosses 36, 38.

Accurately machined tapered projections 66, 68 are provided on each plate to interfit with the tapered slots 28, 30 in the base. The snug interfit at 63 and 65 between these projections and slots locate the plate exactly with respect to the base. A definite clearance 67 exists between the bottom of each projection (52) and the bottom of each slot (30). This serves to allow a snug Wedging interfit at 63 and 65 (FIG. 8). It also serves to prevent a rocking effect of the plate 16 with respect to the base 18, since allowing pads 72 to accurately vertically align the plate firmly on the base in a manner to be described. It will be readily understood that a slight rocking action or slight clearance between the pads 72 and. the base would cause the plate to either bend or crack, depending upon its nature, when struck repeatedly and vigorously with a forming mallet. The upper surface of plate 16 comprises this forming surface 70 for the specific configuration and pitch needed for the particular type and size of propeller blade.

On the lower surface of the forming plate around the periphery thereof is a series of accurately machined, downwardly extending, spaced pads 72, each formed with a particular height to cause firm contact on the support area 32 of the base. The height of the adjacent pads varies around the periphery to cause exact conformation and vertical alignment of the particular forming plate with the universal base element. These pads prevent any rocking motion about the mounting points. The base support area 32 is also accurately machined. The pads may be substituted by a continuous shoulder if desired, or some other structure capable of performing the vertical alignment and firm interfitting features. The spaced pads, however, are preferred due to the fact that with these pads, exact alignment is far easier to obtain since a large share of the surface area to be machined to exact tolerances is removed and substituted by space.

Exact radial alignment or displacement of the plate with respect to the orifice 22 and the remainder of base 18 is achieved by providing openings 54 and 56 which closely interfit with inserted studs 58 and 60 that are threaded into threaded openings 40 and 42 in the base. Therefore, with these three position controls, i.e. circumferential, radial, and vertical alignment means, any plate can be exactly located on the universal base.

Operation In a service shop which repairs boat propellers that have been bent or otherwise damaged, the owner will need an inventory consisting of one universal base casting 18, and a series of mounting plates 16 each of a different pitch to service the range of propellers encountered. As new propellers are adopted, he merely orders additional attachable shaping plates to supplement his inventory stock.

When a boat owner brings a damaged propeller into the service shop, e.g. a bent propeller to be reshaped into the exact original configuration, the serviceman merely selects the plate having the appropriate forming surface 70, places the tapered projections 66, 68 into the tapered slots 28, 30 (circumferential alignment), presses the plate pads 72 into firm contact with the base area (vertical alignment), and then inserts and tightens studs 58, 60 through openings 54, 56 into threaded sockets 40, 42 (radial displacement alignment). He then places propeller 12 onto a suitable post 24 so that one blade 14 extends over the forming surface 70 of plate 16, and reshapes the deformed portions of the blade, using conventional forming tools, to impart to it the desired configuration.

Since marine propellers today are subjected to highspeed operation, the reshaped blade must conform exactly to the other blade or blades on the hub for balanced action. This is true even though the blade axis is offset, i.e. not normal to the hub axis, and the curvature is extremely complex geometrically. Therefore, each forming plate must be adapted to repeatedly correspond exactly with the hub mounting means in an accurate manner in order for the assembly to be effective. The vertical and radial alignment means are consequently of great importance to this invention.

Various other advantages in addition to those already enumerated will appear to those in the art upon studying the foregoing specification, along with certain obvious modifications of the apparatus depicted. Thus, the invenis not to be limited by the illustrated form, but only by the scope of the appended claims according to the principles taught, and the reasonably equivalent structures thereto.

I claim:

1. A pitch block assembly forshaping a propeller blade comprising: a universal support base including means for mounting the hub of a propeller; said base including support area adapted to support a removable forming plate; said support area including a predetermined line area of a predetermined elevational contour and lateral configuration; a configurated forming plate removably supported on said area to support the blade of a propeller to be formed thereon by hammering; said plate having protrusion means extending downwardly from the bottom surface thereof and having a lateral configuration conforming to the lateral configuration of said support area, the lower extremities of said protrusion means conforming to the said contour of said support area and the height of said protrusion means is determined by the shape of said forming plate; and removable connection means between said plate and base adapted to removably secure said plate firmly to said base while allowing removal thereof for replacement by another configurated forming plate.

2. A pitch block assembly for shaping a propeller blade comprising: a universal support 'base including means for mounting the hub of a propeller; said base including support area adapted to firmly support a removable forming plate; said support area'including a predetermined line area of a predetermined elevational contour and lateral configuration; a configurated forming plate removably and firmly supported on said area to support the blade of a propeller to be formed thereon by hammering; interfitting said plate having protrusion means extending downwardly from the bottom surface thereof and having a lateral configuration conforming to the lateral configuration of said support area, the lower extremities of said protrusion :means conforming to the said contour of said support area and the height of said protrusion means is determined by the shape of said forming plate; alignment means between said plate and base; and removable connection means between said plate and base adapted to removably secure said plate to said base.

3. A pitch block assembly for shaping a propeller blade comprising: a universal support base including means for mounting the hub of a propeller; said base including support area adapted to support removable forming plates; said support area including a predetermined line area of a predetermined elevational contour and lateral configuration; a forming plate of selected configuration supported firmly on said area; said plate having protrusion means extending downwardly from the bottom surface thereof and having a lateral configuration conforming to the lateral configuration of said support area, the lower extremities of said protrusion means conforming to the said contour of said support area and the height of said protrusion means is determined by the shape of said forming plate; circumferential alignment means between said base and said plate aligning said forming plate with respect to said hub mounting means; vertical alignment means between said plate and said base creating a vertically aligned and stable condition therebetween; and removable connection means between said plate and base removably securing said plate to said base in a radially aligned position, whereby plates of difiFerent configurations can be interchangeably attached to said base with facility in a firmly supported and accurately aligned manner.

4. A pitch block assembly for shaping a propeller blade comprising: a universal support base including means for mounting the hub of a propeller; said base including support area adapted to support removable forming plates; said support area including a predetermined line area of a predetermined elevational contour and lateral configuration; a configurated forming plate removably supported on said area to support the blade of a propeller to be formed thereon -by hammering; said plate having protrusion means extending downwardly from the bottom surface thereof and having a lateral configuration conforming to the lateral configuration of said support area, the lower extremities of said'protrusion means conforming tothe said contour of said support area .and the height of said protrusion means is determined by the shape of said forming plate; circumferential align-ment means between said base and said plate comprising a plurality of accurately machined interfitting recess means and projection means adapted to align said forming plate with respect to said hub mounting means; vertical alignment means between said plate and said base adapted to create a vertically aligned and stable condition; and radial position controlling and connection means between said plate and base adapted to removably secure said plate to said base.

5. A pitch block assembly for shaping and setting the pitch of propeller blades comprising: a universal support base including means for mounting a propeller hub thereon; an upper support area on said base; said support area including a predetermined line area of a predetermined elevational contour and lateral configuration; a forming plate removably supported on said support area and having a configurated upper forming surface for receiving the blade of a propeller mounted on said mounting means for forming said blade by hammering; said plate having protrusion means extending downwardly from the bottom surface thereof and having a lateral configuration conforming to the lateral configuration of said support area, the lower extremities of said protrusion means conforming to the said contour of said support area and the height of said protrusion means is determined by the shape of said forming plate; one of said plate and base having a plurality of oriented tapered slots; the other of said plate and base. including a plurality of tapered projections adapted to accurately interfit with said tapered slots to circumferentially align said plate with respect to said hub mounting means on said base; and releasable connecting means between said plate and said base adapted to control the radical displacement of said plate with respect to said hub mounting means, whereby each of a plurality of plates having different configuration may be removably attached to said base.

6. A pitch block assembly for forming and setting the pitch of propeller blades comprising: a support base ineluding means for mounting a propeller hub thereon; in

ly from the bottom surface thereof and having a lateral configuration conformingto the lateral configuration of said support area, the lower extremities of said protrusion means conforming to the said contour of said support area and the height of said protrusion means is determined by the shape of said forming plate; said protrusion means of said plate including a plurality of downwardly extending, accurately machined, spaced mounting pads thereunder adapted to contact said support area in a vertically aligning, stable manner; and releasable connecting means between said plate and said base, whereby each of a plurality of plates having different configurations may be removably attached to said base.

7. A pitch block assembly for shaping and setting the pitch of propeller blades comprising: a support base including means for mounting a propeller hub thereon with a blade of said propeller extending over said base and having a plurality of tapered slots; an upper support area on said base; said support area including a predetermined line area of a predetermined elevational contour and lateral configuration; a forming plate removably supported on said support area and having an upper surface adapted to form the :blade of a propeller mounted on said mounting means; said plate having protrusion means extending downwardly from the bottom surface thereof and having a lateral configuration conforming to the lateral configuration of said support area, the lower extremities of said protrusion means conforming to the said contour of said support area and the height of said protrusion means is determined by the shape of said forming plate; said protrusion means of said plate including a plurality of mounting pads thereunder adapted to contact said support area in a vertically aligning, stable manner; said plate including a plurality of tapered projections adapted to interfit with said tapered slots to circumferentially align said plate with said hub mounting means; and releasable connecting means between said plate and said base, whereby a plurality of plates having diiferent configuration may be removably attached to said base.

References Cited by the Examiner UNITED STATES PATENTS 1,093,320 4/1914 Dieckman 786 2,013,705 9/1935 Warren 153-62 2,206,088 7/1940 Gordon 76107 2,916,074 "12/ 1959 Lorenz l53-32 3,039,512 6/ 1962 Den Herder 72457 CHARLES W. LANHAM, Primary Examiner.

WHITMOR-E A. WILTZ, Examiner.

G. L. MILHOLLIN, R. J. I-I'ERiBST, Assistant Examiners. 

1. A PITCH BLOCK ASSEMBLY FOR SHAPING A PROPELLER BLADE COMPRISING: A UNIVERSAL SUPPORT BASE INCLUDING MEANS FOR MOUNTING THE HUB OF A PROPELLER; SAID BASE INCLUDING SUPPORT AREA ADAPTED TO SUPPORT A REMOVABLE FORMING PLATE; SAID SUPPORT AREA INCLUDING A PREDETERMINED LINE AREA OF A PREDETERMINED ELEVATIONAL CONTOUR AND LATERAL CONFIGURATION; A CONFIGURATED FORMING PLATE REMOVABLY SUPPORTED ON SAID AREA TO SUPPORT THE BLADE OF A PROPELLER TO BE FORMED THEREON BY HAMMERING; SAID PLATE HAVING PROTRUSION MEANS EXTENDING DOWNWARDLY FROM THE BOTTOM SURFACE THEREOF AND HAVING A LATERAL CONFIGURATION CONFORMING TO THE LATERAL CONFIGURATION OF SAID SUPPORT AREA, THE LOWER EXTREMITIES OF SAID PROTRUSION MEANS CONFORMING TO THE SAID CONTOUR OF SAID SUPPORT AREA AND THE HIGH OF SAID PROTRUSION MEANS IS DETERMINED BY THE SHAPE OF SAID FORMING PLATE; AND REMOVABLE CONNECTION MEANS BETWEEN SAID PLATE AND BASE ADAPTED TO REMOVABLY SECURE SAID PLATE FIRMLY TO SAID BASE WHILE ALLOWING REMOVAL THEREOF FOR REPLACEMENT BY ANOTHER CONFIGURATED FORMING PLATE. 